The present invention relates to a process for producing an azo group-containing polymer having an azo group in the main chain of a high polymer (hereinafter referred to as "azo group-containing polymer").
Azo compounds, which are generally decomposed by heat and produce radicals, serve as polymerization initiators. The azo compounds are also useful as modifiers and compatibilizers of various resins.
As to a method of synthesizing a polymer having an easily decomposable azo group, the following methods, for example, have been proposed:
(1) a method of producing a polymer having an azo group in a side chain by copolymerizing a vinyl monomer having an azo group in a side chain with another vinyl monomer (Makromol. Chem.,180 609 (1979)),
(2) a method of producing a polymer having an azo group in a side chain by reacting a hydroxyl group containing polymer with a carboxyl group-containing azo compound (Makromol. Chem.,36 17 (1959)),
(3) a method of producing a polyurethane containing an azo group in the main chain by reacting a glycol having an azo group with a diisocyanate compound (Angew. Makromol. Chem., 1 92 (1967)),
(4) a method of synthesizing an azo group-containing polyamide or polyester from a dicarboxylic acid chloride and a diamine or a glycol (Polymer Theses 33 (3) 131 (1976), J. Polym. Sci. A Polym. Chem.,24 406 (1986)), and
(5) a method of producing a polycarbonate having an azo group in the main chain from an azo group-containing dicarboxylic acid chloride and bisphenol A (Japanese Patent Laid-Open (KOKAI) No. 59-27908 (1984)).
Any of the azo group-containing polymers produced by these methods is a material useful for the production of a block copolymer and a graft copolymer. These methods, however, have the following defects. For example, in the method (1), the synthesis of an azo group-containing vinyl monomer is complicated, while in the method (2), it is difficult to completely react an azo compound in the polymerization reaction. The methods (4) and (5) are complicated because it is necessary to synthesize an azo group-containing dicarboxylic acid chloride before the synthesis of an azo group-containing polymer. As to the method (5), it is described that an azo group-containing polycarbonate resin can be produced by using an azo group-containing diacid halide, diol, dialkylene halide and dicarboxylic acid, but interfacial polymerization is difficult except for using diacid halide.
As a result of the studies undertaken for solving the above-described defects, the present inventors have found that it is relatively easy to produce an azo group-containing polymer by the polycondensation of a compound which has an azo group in the main molecular chain and an alcoholic hydroxyl group, phenolic hydroxyl group, imino group or amino group at both ends thereof, with a dicarboxylic acid chloride or a carbonate precursor (except for the polycondensation of a compound having an azo group in the main molecular chain and an alcoholic hydroxyl group at both ends thereof, with a carbonate precursor). The present invention has been achieved on the basis of this finding.